Wireless charging of an electronic device is a desirable convenience as the requirement to physically connect the device to a wire, dock or other physical component while charging is removed.
Some devices are capable of communicating with each other according to the near-field communication (NFC) standard or radio frequency identification (RFID) standard. According to these standards, one device (a reader) can communicate with another device (a tag). The tag may also harvest power from an electromagnetic signal transmitted by the reader, so that the tag may not require any other power source. The tag device has an antenna that is resonant at a frequency on which NFC (or RFID) communications are transmitted from the reader in order to be able to receive as much energy as possible from the signal. This allows the tag to extract as much energy as possible for powering the device as well as ensuring communication reliability.